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In children with a complex febrile seizure, on which patients might you safely forego a lumbar puncture (LP)?

A retrospective study by Seltz et al evaluated 390 cases of complex febrile seizures in 366 children ages 6 months to 6 years in the post-Hib and post-pneumococcal vaccine era.1 The authors evaluated the incidence of either bacterial meningitis or herpes encephalitis. A lumbar puncture (LP) was performed on 146 of 390 cases (37 percent). Of 390 total complex febrile seizures, there were six cases of meningitis (1.5 percent; 95 percent confidence Interval [CI] 0.6–3.3 percent) and one case of HSV encephalitis (0.3 percent; 95 percent CI, 0–1.4%). All children with meningitis or HSV encephalitis demonstrated persistent altered mental status after the complex febrile seizure. There were no cases of meningitis or encephalitis in children with normal mentation following their complex febrile seizure or in any children who did not receive an LP, suggesting that the incidence of meningitis and encephalitis is low in children with complex febrile seizures—particularly those who have returned to their baseline mentation.

Kimia et al retrospectively studied 526 children ages 6 months to 60 months with a first-time complex febrile seizure, evaluating this population for bacterial meningitis specifically.² Of note, they did not evaluate for herpes encephalitis. In this population, 340 of 526 children (64 percent) received an LP, and bacterial meningitis was identified in three of 526 cases (0.9 percent; 95 percent CI, 0.2–2.7). Of these three positive bacterial meningitis cases, two children presented before conjugated pneumococcal vaccines were commonly in use and had altered mental status. The third child was treated for suspected acute bacterial meningitis. She looked well on exam but had a cerebrospinal fluid (CSF) sample “contaminated with blood” that grew no bacterial pathogens on CSF culture. No CSF cell count was ordered, but she had a positive blood culture for S. pneumoniae and was treated as suspected bacterial meningitis. This child also had significant hypocalcemia consistent with rickets. Like the prior study, the incidence of meningitis was very low, especially in a well-appearing child.

A separate retrospective study by Hardasmalani and Saber found similar results in 71 children with complex febrile seizures.³ One patient (1.4 percent) had meningitis, and that patient presented in status epilepticus. Another retrospective study by Rivas-García et al found no cases of meningitis or encephalitis in 654 cases of febrile seizures consisting of 537 simple febrile seizures (82 percent) and 117 complex febrile seizures (18 percent).⁴ In the complex seizure group, 46 had prolonged seizure more than 15 minutes, six had focal seizures, and 76 had multiple seizures within 24 hours. Another retrospective study by Fletcher and Sharieff identified 193 children with first-time complex febrile seizures; 136 received an LP.⁵ There was a single case of acute bacterial meningitis, and that patient had four seizures, of which one lasted more than 30 minutes.

A five-year multicenter retrospective study from seven pediatric emergency departments by Guedj et al evaluated 839 children with complex febrile seizures.⁶ Particularly, the authors were interested in the incidence of meningitis or encephalitis in children with a “clinical exam not suggestive of meningitis or encephalitis,” defined as a normal baseline neurological exam without altered mentation or meningeal signs. LPs were performed in 260 of 839 of patients (31 percent) overall and only 147 of 630 well-appearing children (23 percent). There were no cases of meningitis or encephalitis in the well-appearing group.

While these studies suggest that the incidence of meningitis and encephalitis is very low after a first complex febrile seizure—especially in children who are well-appearing—it is important to note that these studies are retrospective in nature.

Conclusion

After a complex febrile seizure, well-appearing children who have returned to their baseline and have a normal neurological exam can probably forego the lumbar puncture. Because these studies are retrospective in nature, caution should be employed when exercising this treatment strategy. 

References

1. Seltz LB, Cohen E, Weinstein M. Risk of bacterial or herpes simplex virus meningitis/encephalitis in children with complex febrile seizures. Pediatr Emerg Care. 2009;25(8):494-497.
2. Kimia A, Ben-Joseph EP, Rudloe T, et al. Yield of lumbar puncture among children who present with their first complex febrile seizure. Pediatrics. 2010;126(1):62-69.
3. Hardasmalani MD, Saber M. Yield of diagnostic studies in children presenting with complex febrile seizures. Pediatr Emerg Care. 2012;28(8):789-791.
4. Rivas-García A, Ferrero-García-Loygorri C, González-Pinto LC, et al. Simple and complex febrile seizures: is there such a difference? Management and complications in an emergency department. Neurologia (Engl Ed). 2019;S0213-4853(19)30079-9.
5. Fletcher EM, Sharieff G. Necessity of lumbar puncture in patients presenting with new onset complex febrile seizure. West J Emerg Med. 2013;14(3):206-211.
6. Guedj R, Chappuy H, Titomanlio L, et al. Do all children who present with a complex febrile seizure need a lumbar puncture? Ann Emerg Med. 2017;70(1):52-62.e6.